The invention relates to a device for generating reliable status signals of a vehicle that is movable along a given path of travel.
With known devices of this kind (e.g. DE 33 03 961 C2), a position transmitter in form of a measuring strip is mounted on one side of a guideway destined for magnetic levitation vehicles, said measuring strip being provided for example with markings configured as slots which contain absolute information in encoded form on the location at which they are mounted. A data acquisition (detection) unit is provided at the vehicle by means of which the absolute location data are read-out. The read-out location data are for example transmitted in a wireless mode to a central vehicle and guideway control unit accommodated in a master control station.
Furthermore it is known for magnetic levitation vehicles driven by long-stator linear motors (DE 31 48 007 C2) to provide the vehicles with a data acquisition unit in form of a groove measuring (counting) unit connected to a meter and utilized to scan the grooves of the long-stator and to generate periodical signals fluctuating with the spacing (pitch) of the grooves. Though these signals are particularly utilized for producing an optimal phase relation between the long-stator and the vehicle, they may also serve to determine a relative location information by evaluating the counter reading. With known magnetic levitation railways, this is accomplished by resetting the groove counting meter from each read-out absolute location information back to zero so that the present counter reading always indicates the distance of the vehicle from the latest absolute location.
A disadvantage of the location identification as described hereinabove lies in the fact that it is not adequately reliable (safe), because the described data acquisition units, measuring facilities, measuring strips etc. as well as other components of the device described above may fail to work at any time due to a defect. But for controlling particularly a driverless vehicle like e.g. a magnetic levitation railway, safe data and information on the present location of the vehicle are of crucial importance. On the basis of this location information, the traveling speed and the stop of the vehicles at railway stations or, in case of a danger, at other preselected stopping points is adapted. The correctness and availability of the actual location information, therefore, sets the basis for a safe and secure operation control.
The same applies to the speed and direction signals generated in the vehicle. For example, these signals can be derived from the location information by permanently determining the number of long-stator grooves being passed by a vehicle per time unit and having a constant length or by determining by the aid of two data acquisition units mounted in staggered arrangement in the direction of travel the direction in which absolute location data mounted at the guideway are moved past the vehicle. If location data are not safe, the data on speed and direction are also not safe.
For standardization of terms, the signals of location, speed and direction are summarized hereinafter under the collective term “status signals”.